1899] REGENERATION 307 



upper beak of which was accidentally broken off in the middle, and 

 the lower one being sawn off to the same length, both were completely 

 regenerated." 



Until quite recently there seemed no warrant for the assumption 

 that the breaking of the beak in birds was of frequent occurrence, as no 

 other similar observations were recorded. This case, therefore, seemed 

 to indicate that the capacity for regeneration in a part does not 

 depend on special adaptation to a great liability to loss, combined 

 with high biological value of the organ, but rather that it is due 

 to a general adaptation, — to a power of regeneration possessed by the 

 whole organism which, to a certain extent, may come into operation 

 in any part in which loss occurs, even though the loss takes place 

 quite exceptionally. 



This apparent contradiction of the adaptation-theory of regenera- 

 tion is now set aside by the observations of Bordage, who observed 

 that, in the island of Reunion, where the sport of cock-fighting is 

 popular, injuries to the beaks of the cocks are of frequent occurrence, 

 and are regularly followed by regeneration. Bordage found that, as 

 the result of a fight, the beaks of the cocks were often damaged, but 

 that afterwards complete regeneration took place. The injuries were 

 partly inflicted by blows with the beak, partly by " un terrible coup de 

 patte," but they usually affected at most only the terminal third of 

 one or both jaws, — " that part of the upper mandible which represents 

 the premaxillae or unpaired inter-maxillary resulting from the fusion 

 of the premaxillae, and of the lower mandible the triangular portion 

 formed by the fusion of the two bones at their extremity." These 

 parts of the beak may be entirely broken off, when regeneration takes 

 place, and both the bones and their horny covering are renewed. 



In rare cases, the injuries to the lower mandible are so great that 

 it is broken and hangs down, and has to be artificially fixed in its 

 place. In such a case, of course, the animal cannot pick up its food, 

 and has to be artificially fed, for the regeneration of the lower 

 mandible requires two or three months. 



Although these observations refer only to cock-fighting instigated 

 by man, they have, as the author rightly points out, a wider bearing. 

 It is well known that the males of numerous birds fight fiercely with 

 one another in the breeding-season, the beak being naturally the chief 

 weapon, and that this is true of storks was known to Brehm, who says 

 that jealousy often leads to fatal combats. 



The case described by Kennel can therefore no longer be regarded 

 as evidence against the view of the adaptive nature of regeneration, 

 and thus the one observation which gave ground for referring regenera- 

 tion in a highly-differentiated animal to a general power of regeneration 

 loses its force. In recent years, it is true, the renewal of the artificially 

 removed lens of the eye in Triton has been cited in this connection ; 

 but this is hardly justifiable. I, at least, must own to being surprised 



